Method and apparatus for treatment of waste

ABSTRACT

An apparatus for treating waste material that comprises four major cooperating subsystems, namely a pyrolytic converter ( 24 ), a two-stage thermal oxidizer ( 26 ), a steam generator ( 28 ) and a steam turbine ( 30 ) driven by steam generated by the steam generator. In operation, the pyrolytic converter is uniquely heated without any flame impinging on the reactor component and the waste material to be pyrolyzed is transported through the reaction chamber of the pyrolytic converter by a pair of longitudinally extending, side-by-side material transporting mechanisms ( 42, 43 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to waste treatment systems. Moreparticularly, the invention concerns waste treatment systems whereby thewaste is processed by an apparatus comprising a thermal-chemicalreaction chamber and a cooperating dual stage thermal oxidizer.

2. Discussion of the Prior Art

Disposal of waste materials, such as trash and garbage has become aserious concern of industrialized nations. Waste is troublesome not onlybecause it represents something that, as a general rule, cannot be usedfor any beneficial purpose, but also because it presents hazards to theenvironment in terms of the space it takes up and the deleteriouseffects it has on living organisms. For a considerable period, thedisadvantages inherent in waste were largely ignored or, at leastafforded little weight when a new process or new product that wouldproduce waste was introduced, the benefits to society that the processor product would bestow being considered paramount. Inevitably, however,the increasing volume of waste and the dangerous conditions presented byit forced more attention to be paid to ways of dealing with thematerial, such that planning for waste treatment often today is animportant consideration in the design of a new process or product.

In general, refuse from community and from various types of industrialfacilities vary widely in composition, and may include, for instance,sludge from sewage, garbage, plastic scraps, tires and other articles ofrubber, scrap wood, oil impregnated rags and refuse oils, all of whichare organic, as well as concrete debris and scrap metal. Theinflammables among these components range widely in heat of combustionfrom about 1,200 kcal/kg up to about 7,000 kcal/kg. Consequently, it hasbeen necessary to use a variety of types of disposal facilities forhandling each type of material.

It has not been possible to treat all of these types of materials byordinary combustion methods because offensive odors have been generatedas a result of imperfect combustion, the production of components whichare extremely corrosive, particularly at high temperature, adherence offly-ash and the presence of substantial amounts of imperfectly combustedcomponents in the residual ash. Disposal of ash also poses problems suchas the scattering of ash dust by means of winds or fouling of water.Moreover, provision must be made for preventing corrosion and damage tothe combustion equipment and instruments and to preventing pollution ofthe environment such as is caused by the gases resulting from thecombustion of chlorinated organic materials. The increase in thequantity of scrap vinyl chloride resins is a factor here.

Conventionally, in the course of incineration, gasification is carriedout by injecting air and steam prior to incineration. The objective isto convert organic materials from different sources into forms, whichwill burn uniformly in the manner of coal, wood or charcoal; however,refuse varies so widely in properties that the reaction velocity ofgasification also varies strongly. Consequently, the difficulty ineffecting complete combustion without harm to the environment has beensuch as to make the incineration operation uneconomical in many cases.

Presently, perhaps the most common method of waste disposal is thesocalled landfill method of disposal. However, because of the very largevolume of waste that is generated on a daily basis particularly inhighly populated areas, acceptable landfill sites are rapidly reachingcapacity and new sites have become difficult to find. Accordingly,alternate methods of waste disposal, such as pyrolytic destruction ofwaste, have been actively considered.

By techniques of pyrolytic decomposition, many types of waste materialscan be converted into energy rich fuels such as combustible gases andchar, or fuel carbon. Accordingly, several types of devices forpyrolyzing refuse and other waste products have been suggested. Many ofthese devices have proved unworkable or economically unfeasible. Others,while feasible in concept have been proven to be inefficient andunreliable in continuous operation. Still others, while attractive intheory, have been shown to be too expensive to manufacture, install andoperate.

Among the most successful prior art refuse conversion devices are thedevices described in U.S. Pat. Nos. 2,886,122; 2,993,843; 3,020,212; and3,098,458. The present invention constitutes an improvement upon certainof the devices described in these patents.

The pyrolytic process employs high temperature in, most desirably, anatmosphere substantially free of oxygen (for example, in a practicalvacuum), to convert the solid organic components of waste to otherstates of matter, such pyrosylates in a liquid or vapor phase. The solidresidue remaining after pyrolysis commonly is referred to as char, butthis material may contain some inorganic components, such as metals, aswell as carbon components, depending on the nature of the startingwaste. The vaporized product of pyrolysis further can be treated by aprocess promoting oxidation, which “cleans” the vapors to eliminate oilsand other particulate matter therefrom, allowing the resultant gasesthen to be safely released to the atmosphere.

A typical waste treatment system utilizing pyrolysis includes an inputstructure for introducing the waste; a chamber or retort from which aircan be purged and in which pyrolysis processing occurs; and means forraising the temperature inside the chamber.

Systems that rely upon pyrolysis often are designed with principalattention being given to system efficiency. For example, to encourageconsistent results from the pyrolytic conversion process, variousmethods and apparatuses commonly are used to pre-treat the waste beforeit is introduced into the pyrolytic chamber. These include pre-sortingor separating the waste into constituents on the basis of weight,shredding the material to make it of relatively uniform size and perhapsblending it with other pre-sorted material to promote even distributionof the waste as it is introduced into the retort. Several techniqueshave been employed to reduce the level of moisture in the waste beforeintroducing it into the machine, because the presence of moisture makesthe pyrolytic process less efficient. Such techniques include drying bydesiccation or through the application of microwave energy.

Other features often are provided to continuously move waste through thetreatment unit while the system is being operated, such as a form ofconveyance arrangement. Screw conveyors or conveyor belts oriented at anincline have been used to ramp waste material, in units of a definedvolume and at a defined rate of flow, up from a storage bin orpre-treatment assembly at the ground level to a charging hopper at thetop of the treatment unit through which waste is metered into thepyrolytic chamber. Screw conveyors, auger screws and worm conveyors allhave been used to impel waste through the retort while pyrolysis takesplace, again, to encourage predictable results from the process.

The manner in which the retort chamber is supplied with heat energy tosustain pyrolysis also tan affect the efficiency with which the processcan be carried out. For example, it has been found that uniformapplication of heat to the outer wall of the retort, through which it isconducted into the interior of the chamber, reduces the risk that theretort will buckle from uneven distribution of high temperatures andtends to encourage a more even distribution of heat and consistency oftemperature throughout the chamber, which leads to consistent processingresults. System features provided to address even heating have includedthose directed to the manner in which the primary source of heat energy,commonly fuel gases, being combusted in a heating chamber, is arrangedwith relation to the retort, and the number and placement of fuel gasinjection ports, etc.

It further has been known to provide a feature which encourages theefficient use of heat to sustain the pyrolytic process, such as one thatallows the recycling of gases that have once been combusted to supplyheat energy to the pyrolytic chamber back through the gas injectionport, where the gases can be ignited again with a fresh supply of oxygenor air.

Efficiency-promoting elements also can be provided for the processingand recycling of off-gases or vapor pyrosylate. For example, it is knownthat if a pressure gradient is maintained between the retort and the gasprocessing arrangement in the direction of the exhaust, the vaporpyrosylate naturally will tend to flow into the cleaning elements. Toavoid wasting energy, the cleaned high temperature gases can be used toprovide energy to some sort of generating station, such as to heat waterin a boiler that supplies a steam generator.

What has long been needed and heretofore has been unavailable is animproved pyrolytic waste treatment system that is highly efficient, iseasy to maintain, is safe, reliable and capable of operation with a widevariety of compositions of waste materials, is easy to maintain and onethat can be constructed and installed at relatively low cost. The thrustof the present invention is to provide such an improved pyrolytic wastetreatment system.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a pyrolytic wastetreatment system that his highly versatile, is efficient and reliable inoperation and one that is easy to maintain.

Another object of the invention to provide an improved method andapparatus for pyrolyzing waste material and recovering energy producingmaterials therefrom.

It is another object of the invention to provide a method and apparatusof the aforementioned character in which both liquid and solid wastematerials can be processed simultaneously.

Another object of the invention to provide a method and apparatus of theaforementioned character in which waste materials are efficiently andinexpensively converted into energy rich fuels such as combustible gasesand fuel carbon and in which useful chemical by-products are recovered.

Another object of the invention is to provide a method and apparatus forthe complete combustion of mixed refuse without venting noxious orcorrosive gases. Another object of the invention is to provide a methodand apparatus of the aforementioned character which will enhance theoverall heat efficiency of degradation while precluding pollution of theenvironment.

Another object of the invention is to provide an apparatus for treatingwaste material that comprises four major cooperating subsystems, namelya pyrolytic converter, a two stage thermal oxidizer, a steam generatorand a steam turbine driven by steam generated by the steam generator.

Another object of the invention is to provide an apparatus of thecharacter described in the preceding paragraph in which the pyrolyticconverter is heated without any flame impinging on the reactorcomponent.

Another object of the invention is to provide an apparatus of the classdescribed in which the waste material to be pyrolyzed is transportedthrough the reaction chamber of the pyrolytic converter by a pair oflongitudinally extending, side-by-side material transfer mechanisms.

Another object of the invention is to provide an apparatus of thecharacter described in the preceding paragraph in which each of thetransfer mechanisms includes a first screw conveyor section made up of aplurality of helical flights for conveying the heavier waste and asecond paddle conveyor section interconnected with the first section forconveying the partially pyrolyzed waste, the second section comprising aplurality of paddle flights.

Another object of the invention is to provide an apparatus as describedin the preceding paragraph in which the dwell time of the waste materialwithin the reaction chamber can be controlled independently of the feedmechanism that feeds waste material into the reaction chamber.

Another object of the invention is to provide an apparatus in whichliquid feed material can be fed into the pyrolytic converter interiorlyof the waste material transfer mechanisms.

Another object of the invention is to provide an apparatus of the classdescribed in which the thermal oxidizer includes a first and secondstages, the first stage a being used to initially heat the reactorcomponent of the pyrolytic converter.

Another object of the invention to provide an apparatus as described inthe preceding paragraphs which, once operating, is substantiallyself-sustaining and requires a minimum use of outside energy sources forpyrolyzing the waste materials.

It is still another object of the invention to provide an apparatus ofthe character described in which combustible gases generated within thereaction chamber are transferred to the thermal oxidizer and are mixedwith air to produce a highly combustible gas which can be used tosustain the continued pyrolysis of the waste materials within thepyrolytic converter.

It is another object of the invention to provide an apparatus asdescribed in the preceding paragraph in which excess heated gases aretransferred from the second stage of the thermal oxidizer to a steamgenerating subsystem to generate steam for driving a turbine.

It is yet another object of the invention to provide an apparatus asdescribed in the preceding paragraphs which is durable, efficient andhighly reliable in operation.

Finally it is an object of the invention to provide an apparatus of theclass described which is relatively inexpensive to manufacture, issimple to operate and one which can be operated on a substantiallycontinuous basis with a minimum of problems and with little supervision.

These and other objects of the invention are realized by an apparatusand method for pyrolyzing waste materials comprising a pyrolyticconverter having a uniquely configured, multi-chamber reactor and a twostage thermal oxidizer operably interconnected with the pyrolyticconverter. During startup operations the reactor chamber of thepyrolytic converter is controllably heated by the first stage of thethermal oxidizer. Upon reaching an elevated temperature the materials tobe treated are controllably fed into the reactor chamber where they arepyrolyzed. The combustible gases generated within the reaction chamberduring the pyrolysis process are controllably transferred to the secondstage of the thermal oxidizer wherein they are mixed with air. Thegaseous mixture thus formed is transferred to the pyrolytic converterfor combustion to maintain the reactor chamber at the required elevatedtemperature. During operation, the second stage of the thermal oxidizeris maintained at a pressure less than the pressure within the combustionchamber of the pyrolytic converter so that combustible gases within thecombustion chamber will be continuously urged to flow toward the secondstage of the thermal oxidizer. Heated gases are also transferred fromthe second stage of the thermal oxidizer to a steam generating subsystemfor generating steam that can be used to drive a steam turbine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B, when considered together, comprise a side-elevationalview of one form of the apparatus of the invention.

FIG. 1C is an enlarged, side-elevational view of the feed means of theinvention.

FIGS. 2A and 2B, when considered together, comprise an enlarged,sideelevational view of the thermo converter and thermo oxidizercomponents of the apparatus partly broken away to show internalconstruction.

FIG. 3 is an enlarged, cross-sectional view taken along the lines 3-3 ofFIG. 2A.

FIG. 4 is an enlarged, cross-sectional view taken along lines 4-4 ofFIG. 2A.

FIG. 5 is a greatly enlarged, cross-sectional view taken along lines 5-5of FIG. 2A.

FIG. 5A is a greatly enlarged, cross-sectional view taken along lines5Á5A of FIG. 2A

FIG. 6 is a cross-sectional view taken along lines 6-6 of FIG. 2A.

FIG. 7 is a cross-sectional view taken along lines 7-7 of FIG. 2B. FIG.8 is a cross-sectional view taken along lines 8-8 of FIG. 2B. FIG. 9 isa cross-sectional view taken along lines 9-9 of FIG. 2B. FIG. 10 is anenlarged, cross-sectional view taken along lines 10-10 of FIG. 2B.

FIG. 11 is a cross-sectional view taken along lines 11-11 of FIG. 10.

FIG. 12 is a generally perspective, exploded view of one form of barrierring assembly of the thermo oxidizer.

FIGS. 13A and 13B, when considered together, comprise a top plan view ofcomponents shown in FIGS. 2A and 2B.

FIG. 14 is an enlarged, fragmentary view of a portion of the thermooxidizer component showing the barrier ring in a closed position.

FIG. 15 is a fragmentary view similar to FIG. 14 but showing the barrierring in an open position.

FIG. 16 is a block diagram illustrating the operation of the apparatusof the invention.

DESCRIPTION OF THE INVENTION

Referring to the drawings and particularly to FIGS. 1A and 1B, one formof the apparatus of the invention is there shown. The apparatus herecomprises seven major cooperating subsystems, namely a dryer 20, a feedmeans 22, a thermal chemical reactor or pyrolytic converter 24, atwo-stage, thermal oxidizer 26, a steam generator 28, and a steamturbine 30 that is driven by the steam converted by the steam generator.

In the operation of the apparatus of the invention, the waste materialto be treated is first introduced into the dryer subsystem 20 via aninlet 32. After drying in a manner presently to be described, the driedwaste material is controllably fed into the thermal reactor 24 by thenovel feed means 22 which uniquely includes both a solid feed means anda liquid feed means. The solid feed means for feeding solid wastematerial to the converter comprises a gravity fed, bottom surge feedhopper 34 of the, general construction shown in FIG. 1C. As will bedescribed more fully hereinafter, the liquid waste materials can beintroduced into the pyrolytic converter simultaneously with theintroduction of solid materials via the liquid feed means that isgenerally designated in FIG. 1C by the numeral 35. This novel liquidfeed means includes an atomizer means for at least partially atomizingthe liquid waste.

As illustrated in FIGS. 2A, 213, and 5, the novel thermal reactor orpyrolytic converter subsystem 24 of the present form of the invention isof a unique configuration that comprises a hollow housing 34 havingfirst and second ends 34 a and 34 b. Disposed within housing 34 is areaction chamber 36 that is defined by an elongated hollow structure 38that in cross section has a novel three dome, generally triangularconfiguration (FIG. 5). Structure 38 is preferably constructed from acastable refractory material capable of withstanding temperatures inexcess of 3200 degrees Fahrenheit. As shown in FIG. 5, chamber 36includes first and second longitudinally extending, semicircular shaped,subchambers 30 a and 36 b. Extending longitudinally of chamber 36 a is afirst conveyor means, or conveyor mechanism 40. Extending longitudinallyof chamber 36 b is a similarly configured second conveyor means orconveyor mechanism 42. These conveyor mechanisms 40 and 42 are of anovel construction with each comprising a first helical screw section 43for conveying less pyrolyzed and, therefore, more dense waste and asecond paddle like section 45 for conveying the more pyrolyzed, lessdense waste (see FIGS. 5 and 5A). The twin conveyor mechanisms aremounted within the reactor using conventional bearings 41 and arecontrollably rotated by conventional drive means 41 a of the chambershown in FIG. 6.

The upper portion 36 c of reaction chamber 36 functions to permitgenerated gases within the chamber to expand and, in a manner presentlyto be described, to be transported from the reaction chamber via achamber outlet 44 (FIG. 2A). As illustrated in FIGS. 2A and 5, the innersurfaces 34 c of the hollow housing 34 within which the reactor chamberis mounted, are covered by a ceramic fiber insulation 46 that isconnected to the inner walls of the housing by suitable fasteners. Aswill presently to be described, the area between the inner surfaces 34 cof the housing and the ceramic reaction chamber 38, is initiallycontrollably heated by the first stage of the thermal oxidizer 26.

Turning particularly to FIGS. 2B, 6, and 7, the thermal oxidizer 26, ofthe present form of the invention, includes a hollow housing 47 havingan inner wall 47 a. Disposed between the inner and outer wall is aceramic fiber insulation 49. Within housing 47 is a first stage definedby a first subchamber 50 and a second stage defined by a secondsubchamber 52. Dividing subchambers 50 and 52 is a novel baffle meansfor controlling the flow of gases between the chambers. This bafflemeans here comprises a novel barrier ring assembly 56 that comprises apair of fixedly mounted semicircular segments 57 (FIG. 15) and apivotally mounted assembly 58. Assembly 58 is made up of a pair ofsemicircular segments 59 that are affixed to a ceramic baffle plate 60(see FIG. 12). As illustrated in FIGS. 12, 13B and 15, the baffle ringassembly 56 is movable between the first and second positionsillustrated by the solid and phantom lines in FIG. 13B. Thermal oxidizer26 is also is also capable of withstanding temperatures in excess of3000 degrees Fahrenheit.

Thermal oxidizer 26 further includes a first stage heater means forcontrollably heating subchamber 50 and second stage heater means forcontrollably heating subchamber 52. In the present form of theinvention, the first stage heater means comprises a first burnerassembly 62 that includes a generally cylindrically shaped housing 64(FIG. 7) that is connected to the first end 26 a of thermal oxidizer 26in the manner best seen in FIG. 2B. Housing 64 carries fourcircumferentially spaced gas burners 66 that are of conventionalconstruction and function to initially heat subchamber 50 at time ofstartup. Similarly, the second stage heater means here comprises asecond burner assembly 70 that is mounted in housing 47 intermediatesubchambers 50 and 52 in the manner shown in FIG. 2B. As best seen inFIG. 9, second burner assembly 70 comprises four circumferentiallyspaced gas burners 72 that are also of conventional construction andfunction to initially heat second subchamber 52 at the time of startup.Burners 66 and 72 are of a conventional construction and arecommercially available from sources such as Eclipse Combustion, Inc. ofRockford, Ill., U.S.A.

First subchamber 50 has an outlet port 74 that is in communication witha port 76 formed in reactor 24 via a conduit 78 (FIGS. 1A and 1B). In amanner presently to be described, reaction chamber 36, which preferablyoperates at less than five percent (5%) oxygen is initially heated in aflame-free manner by heated gases transferred from subchambers 50 and 52of the thermal oxidizer to upper chamber 36 c of reaction chamber 36.

Second subchamber 52 of the thermal oxidizer has an outlet port 82 thatcommunicates with an inlet port 84 of the steam generator subsystem 28via a conduit 86. Steam generator subsystem 28, which includes a highpressure steam tank 28 a and a lower mud drum 28 b, is of a conventionaldesign and is readily commercially available from various sources as,for example, Babcock Wilcox of Mississippi. Drum 28 b is provided with aplurality of cleanout assemblies 85 for periodically removing sludge andthe like from the drum. As shown in FIG. 1B, drum 28 b is interconnectedwith tank 28 a by a plurality of spaced-apart, connector tubes 89 and isalso connected with a water supply here provided in the form of make-upwater tank 88. The water contained within tank 88 is pumped to drum 28 bvia conduit 87 by a conventional pumping system 90 (FIG. 1B) and isconverted to high-pressure steam within the connector tubes 89 which areimpinged upon by the heated gases transferred from the thermal oxidizer26 to the steam generator via conduit 86.

In system operation, the high pressure steam contained within tank 28 ais transferred to steam turbine 30 via a conduit 94. Steam turbine 30,which is of conventional construction and is also readily commerciallyavailable from sources such as De Mag La-Vale, generates electricitythat may be used to power the various electrically driven components ofthe apparatus, such as the pumping system 90. The steam exhausted fromsteam turbine 30 is carried to a conventional condenser 96 via a conduit98. The water formed in condenser 96 is then transferred to a coolingtower 100, which is also of conventional construction, via a conduit102. The water that has been cooled within the cooling tower 100 isreturned to condenser 96 via a conduit 104 and is then transferred totank 88 via a conduit 106 (FIG. 1B).

As shown in FIGS. 1A and 1B, a portion of the waste gases flowingthrough steam generator 28 is first cooled with dilution air and is thentransferred to the dryer subsystem 20 via a diverter valve 110 and aconduit 112. These hot waste gases at a temperature of about 550 degreesFahrenheit are used to efficiently dry the waste contained within thedryer 20. From dryer 20 the gases are returned to the thermal oxidizervia an overhead conduit 114 (FIG. 1B). The portion of the gases from thesteam generator that are not diverted to the dryer are transferred to acondensed scrubber apparatus 118 which effectively removes harmfulcontaminants from the exhaust gases so that the gases can be safelydischarged to atmosphere via a conventional blower unit 120. Scrubberapparatus 118 is commercially available from various sources such as C.W. Cole Fabricators, Inc. of Long Beach, Calif. Similarly, blower unit120 is readily available from sources such as New York Blowers Co. ofWillow Brook, Ill.

In operating the apparatus of the invention, the baffle assembly 56 ofthe thermo oxidizer 26 is moved into a closed position wherein chamber50 is substantially sealed relative to chamber 52. This done, burners 72of burner assembly 70 are ignited to controllably heat chamber 52 to atemperature sufficient to cause the water contained within tubes 89 ofthe steam generator apparatus 28 to be converted into high-pressuresteam. When tank 28 of the steam generating system is filled withpressurized steam, the steam can be conveyed to the turbine generator 30via conduit 94. With the generator 30 in operation, sufficientelectricity can be generated to operate the various electricalcomponents of the apparatus including the pumping system 90 which isused to pump water to the make-up tank 88.

Once sufficient power is being generated by generator 30 to operate theelectrical system, burners 66 of burner assembly 62 can be ignited inorder to controllably heat chamber 50. When the gases within chamber 50reach a temperature sufficient to pyrolyze the waste material that iscontained within dryer 20, the material can be transferred to the feedmeans by transfer means shown here as a conventional waste conveyor 120.As previously mentioned, the material within dryer 20 is dried by theexcess gases flowing from the thermal oxidizer through the steamgenerator and into conduit 112 via diverter valve 110. Once the gaseswithin chamber 50 have reached the pyrolyzing temperature, they aretransferred to the reactor chamber via conduit 78, to heat the reactorchamber to a pyrolyzing temperature. When this has been achieved, baffleassembly 56 can be moved into the open position shown in FIG. 2B and thefeeding of the dried waste can begin.

As the waste material, being transferred to the hopper by waste conveyor120, starts to flow into the hopper 34, the upper butterfly valve 122 ofthe hopper system is moved into the open position shown in FIG. 1C ofthe drawings and the lower butterfly valve 124 is moved into a closedposition blocking any transfer of waste material from the hopper intothe auger portion 126 of the feed assembly. Once intermediate chamber128 of the feed assembly is filled with the waste to be pyrolyzed, avacuum is drawn within chamber 128 by a vacuum pump “V” that isinterconnected with chamber 128 by a conduit 130 (FIG. 1C). Afterchamber 128 has been suitably evacuated, butterfly 124 is moved into anopen position permitting the waste contained within chamber 128 to flowinto the auger conveyor means of the feed assembly without jeopardizingthe integrity of the vacuum within the reactor chamber. As is indicatedby the arrow 129 in FIG. 1C, the dried waste material entering thechamber 130 that contains the conveyor screw 133 is controllably fedinto the reactor chamber via hollow shaft 132 and inlet 134 of thereactor chamber (FIG. 2A).

The waste material entering the, reactor chamber will fall downwardly inthe direction of the arrow 135 of FIG. 2A in a direction toward thescrew conveyors 43. As illustrated in FIG. 5, the waste material flowinginto chamber 36 will impinge upon the elongated, angular shapeddistribution member 136 that is disposed within chamber 36 (see alsoFIG. 2A). As the waste being introduced into the reactor impinges ondiverter member 136, the waste will be directed toward the two twinconveyors 40 and 42 in the direction of the arrows of FIG. 5. It is tobe understood that with the construction just described, waste materialscan be controllably metered into the reactor chamber 36 and evenlydistributed between the two screw conveyors 40 and 42.

The waste material introduced into chamber 36 in the manner justdescribed will be carried forwardly of the reactor by the helical screws40 and 42 and, as it travels forwardly of the reactor will be undergopyrolyziation due to the elevated temperature of the reactor chamber. Bythe time the waste material reaches the end of the screw conveyor,sections 43, it will have been substantially reduced to carbon formwhich is of a lesser density that will permit it to be transferredthrough the remaining length of the reactor chamber by the novel paddleconveyors 45 that are of a construction best seen in FIG. 5A.

Turning once again to FIG. 1C, it is to be noted that the apparatus ofthe invention further includes a fluid waste tank 140 that is adapted tostore fluid waste as, for example, waste oil. Because of the novelconstruction of the feed means of the invention, the waste fluid can bedisposed of simultaneously with the disposal of the solid waste. When itis desired to dispose of the fluid waste contained within tank 140, aconventional pumping means 142, which is shown here as a conventional,progressive, cavity, positive displacement pump 142, is used to transferthe fluid from vessel 140 to the atomizing means of the apparatus. Thisnovel atomizing means here comprises the assembly generally designatedin FIG. 1C by the numeral 144. In the present form of the invention, theatomizing means comprises a chicksan rotating joint 145 that permits theintroduction of various carrier gases such as steam into the hollowshaft 146 of the feed means. The atomizing means further includes asteam inlet 148 through which steam at least 400 degrees Fahrenheit fromsteam generator 28 can be contollably introduced in the direction shownby the arrow 149 of FIG. 1C. Steam entering steam inlet 148 will createa venturi effect within a Y-fitting 150 that defines a venturi mixingchamber that is interconnected within a conduit 146 via the chicksanjoint 145. The venturi effect created within fitting 150 will draw thefluid into the venturi chamber where it will be atomized in a mannerwell understood by those skilled in the art. The atomized fluid willthen flow into the previously identified chamber 130 via hollow shaft146. As the atomized fluid enters chamber 130, it will intermix with thewaste material contained therein and will travel with the waste materialinto the reactor in the manner earlier described. It is, of course,apparent that the intermixture of the dried waste material and theatomized fluid will be readily pyrolyzed within the reactor as thematerial is carried forwardly of the reactor by the conveyor means ofthe invention.

It is to be understood that the novel conveyor means of the inventionthat is mounted within the reactor chamber in the manner best seen inFIG. 6 is relatively light weight. In the prior art wherein the conveyorsystems were made up of elongated, helically shaped, screw-typeconveyors, the conveyor was of a substantial weight and, when onlysupported at each end experienced undesirable sagging proximate itscenter. With the novel construction of the present invention, wherein alarge part of each of the screw conveyors comprise the much lighterweight paddle wheel-type construction, the overall weight of theconveyors is substantially reduced when compared to the prior art,single-piece helical screwtype conveyors. Additionally, since conveyorsof the present invention are disposed in a side-by-side relationship,the overall length of the reactor can be substantially reduced from thatwhich would be required if only a single helical type screw conveyorwere to be used. In summary, because of the novel design of the conveyorsystems of the present invention, undesirable sagging of the conveyorsis prevented and, as a result of the twin conveyor design, the length ofthe reactor can be significantly reduced.

When the waste material reaches the second end 34 b of the reactor, thepyrolized waste will be introduced via extensions 156 a into a pair ofside-by-side outlet conduits generally designated in FIG. 4 by thenumeral 156 where the pyrolyzed waste products can be recovered.Extensions 156 a are in communication with the chambers that house theconveyor means so that the waste carried by the conveyor means will beintroduced into outlet conduits 156 in the manner indicated by the arrow160 of FIG. 2A.

As previously mentioned, the heated gases produced by the pyrolyticreactor will be transferred to the thermal oxidizer 26 via outlet 44 andconduit 44 a. A portion of the heated gases produced by the pryolysis ofthe waste material will be returned from the thermal oxidizer to thereactor to sustain the pyrolysis and a portion will be transferred viaconduit 86 to the steam generator subsystem 28 via conduit 86. Theselater heated gases will function to heat the water contained withintubes 89 to convert it to high pressure steam which, in turn, will beused to drive turbine 30. It is important to note that to maintain thedesired transfer of the heated gases, the baffle assembly 56 isstrategically operated so as to continuously create a slight positivepressure within first stage 50. This positive pressure will urge aportion of the heated gases to be return to the reactor via conduit 78to sustain the pyrolysis of the waste. To accomplish this strategicbalance, the pressure differential between chambers 50 and 52 iscontinuously monitored by a differential pressure gauge and the positionof the baffle assembly is precisely regulated by a baffle operatingmeans shown in the drawings as comprising a control mechanism 163.

As best seen in FIGS. 11 and 12, the unique baffle assembly of thepresent invention comprises a generally circular-shaped ceramic plate 60to which a pair of semicircular barrier rings are affixed in the mannerillustrated in FIG. 12. The baffle assembly, which comprises plate 60and the semicircular rings affixed to either side of the plate ismounted for pivotal movement within the thermal oxidizer about an axis159 that is defined by a pair of spaced-apart pivot pins 161. Pivot pins161 are mounted within the wall of the thermal oxidizer housing in themanner shown in FIG. 12 so that the baffle assembly can be pivoted aboutaxis 159 by the control mechanism 163 from a first closed position to asecond open position. As best seen in FIG. 10, the control mechanismhere comprises a drive motor 165 having a drive shaft 165 a that drivesa toothed gear 167 that is drivably connected to upper pivot pin 161. Asis schematically shown in FIG. 14, the differential pressure gauge 169is in communication with both of the chambers 50 and 52 so that thepressure within the chambers can be continuously monitored. Thedifferential pressure gauge is readily commercially available fromseveral sources. However a gauge sold under the name and styleMAGNEHELIC by Dwyer Instruments, Inc. of Anaheim, Calif. has provensatisfactory for the present purpose. In a manner well understood bythose skilled in the art, gauge 169 is operably associated with drivemotor 165 to appropriately operate the motor to open and close thebaffle assembly in a manner to continuously maintain the desiredpressure differential between chambers 50 and 52. As previouslymentioned, when the pressure differential is properly controlled, theheated gases within chamber 50 will controllably flow into the thermalconverter 24 to maintain the pyrolysis of the waste. Accordingly, duringnormal operation, no heat need be added to the system by the gas firedburners 66 and only a pilot flame need be maintained.

By way of summary, during the operational cycle, as illustrated in FIG.16, the municipal waste to be treated is deposited in an incoming pit170. From there the waste is transferred by means of a feed system 172to a conventional shredder 174 which shreds the waste prior to itsintroduction into the previously identified dryer 20. From the dryer,the dried waste is introduced into the thermal converter 24 via thepreviously discussed feed means 22. Heated gases generated in thethermal converter are transferred to the thermal oxidizer 26 in themanner previously discussed. As shown in FIG. 16, a portion of theheated gases contained within the thermal oxidizer is returned to thethermal converter via conduit 78. Another portion of the heated gaseswithin the thermal oxidizer is transferred to the waste-heat boilerwhich forms a part of the previously identified steam generator 28. Asdepicted in FIG. 16, the heat from the waste-heat boiler is transferredto the blender-dryer by conduit 112 to accelerate the drying process. Inturn, the excess gases from the blender-dryer are returned to thethermal oxidizer via conduit 114. A portion of the excess heated gaseswithin the waste-heat boiler 176 are transferred to the wet scrubberand, in the manner previously described, fluids from the wet scrubberare transferred to the water treatment system 178 via a conduit 180.Similarly, gaseous emissions from the wet scrubber are transferred to anadmissions monitoring system 182 to ensure that harmful emissions arenot emitted into the atmosphere. As indicated by the arrow 184, solidrecyclable byproducts are recovered from the thermal converter 24 forappropriate recycling.

Having now described the invention in detail in accordance with therequirements of the patent statutes, those skilled in this art will haveno difficulty in making changes and modifications in the individualparts or their relative assembly in order to meet specific requirementsor conditions. Such changes and modifications may be made withoutdeparting from the scope and spirit of the invention, as set forth inthe following claims.

1. An apparatus for treating waste material comprising: (a) a thermalreactor including a hollow housing and a reaction chamber disposedwithin said hollow housing; (b) feed means connected to said thermalreactor for CONTROLLABLY feeding the waste material to the reactionchamber of said thermal reactor; (c) conveyor means for conveying thewaste material through said reaction chamber of said thermal reactor,wherein said conveyor means comprises a first conveyor mechanism and asecond conveyor mechanism, each of said first and second conveyormechanisms including a first helical screw section and a second paddlesection; and (d) heating means for heating said reaction chamber, saidheating means comprising a thermal oxidizer connected to said thermalreactor for initially heating said reaction chamber.
 2. The apparatus asdefined in claim 1 in which said conveyor means comprises a pair ofconveyor mechanisms rotatably mounted within said reaction chamber in aside-by-side relationship.
 3. The apparatus as defined in claim 1 inwhich said thermal oxidizer includes first and second subchambersdivided by a baffle means for controlling the flow of gases between saidfirst and second subchambers.
 4. The apparatus as defined in claim 1further including drying means operably associated with thermal reactorfor drying the waste material.
 5. The apparatus as defined in claim 1 inwhich said feed means comprises: (a) a waste receiving hopper connectedto said thermal reactor; and (b) a feed screw connected to saidwaste-receiving hopper for CONTROLLABLY transporting the solid wastematerial toward said thermal reactor.
 6. The apparatus defined in claim1 in which said feed means comprises: (a) a waste receiving hopperconnected to said thermal reactor; (b) a feed screw connected to saidwaste receiving hopper for transporting liquid waste material towardsaid pyrolytic converter; and (c) atomizing means connected to said feedscrew for at least partially atomizing the liquid waste material priorto transporting the liquid waste material toward said pyrolyticconverter.
 7. The apparatus as defined in claim 1 in which said thermaloxidizer comprises: (a) a housing having first and second chambers; and(b) baffle means disposed between said first and second chambers forcontrolling the flow of gases therebetween.
 8. The apparatus as definedin claim 1 in which said reaction chamber of said thermal reactorcomprises an elongated, hollow structure having first and secondsubchambers and in which said first conveyor mechanism is mounted withinsaid first subchamber and said second conveyor mechanism is mountedwithin said second subchamber.
 9. The apparatus as defined in claim 1further including a steam generating means connected to said thermaloxidizer for generating steam using heated gases received from saidthermal oxidizer.
 10. The apparatus as defined in claim 7 furtherincluding a steam driven turbine connected to said steam generatingmeans for receiving steam therefrom to drive said turbine.
 11. Anapparatus for treating waste material comprising: (a) a thermal reactorincluding a hollow housing and a reaction chamber disposed within saidhollow housing; (b) feed means connected to said thermal reactor forCONTROLLABLY feeding the waste material to reactor chamber of saidthermal reactor; (c) conveyor means for conveying the waste materialthrough said reactor chamber of said thermal reactor, said conveyormeans comprising a pair of conveyor mechanisms rotatably mounted withinsaid reaction chamber in a side-by-side relationship, wherein each ofsaid conveyor mechanisms comprises a first screw conveyor section and aplurality of paddle flights; (d) heating means for heating said reactionchamber, said heating means comprising a thermal oxidizer connected tosaid thermal reactor for initially heating said reaction chamber, saidthermal oxidizer comprising first and second subchambers divided by abaffle means for controlling the flow of gases between said first andsecond subchambers; and (e) drying means operably associated withthermal reactor for drying the waste material.
 12. The apparatus asdefined in claim 1 in which said feed means comprises: (a) a wastereceiving hopper connected to said thermal reactor; and (b) a feed screwconnected to said waste-receiving hopper for CONTROLLABLY transportingthe waste material toward said thermal reactor.
 13. (canceled)
 14. Theapparatus as defined in claim 11 further including pressure sensingmeans operably associated with said baffle means for sensing pressuredifferential between said first and second subchambers.
 15. Theapparatus as defined in claim 11 further including a steam generatingmeans connected to said thermal oxidizer for generating steam usingheated gases received from said thermal oxidizer.
 16. The apparatus asdefined in claim 15 further including a steam driven turbine connectedto said steam generating means for receiving steam therefrom to drivesaid turbine.
 17. The apparatus as defined in claim 16 in which saidsteam generating means comprises: (a) a water boiler; (b) a source ofwater connected to said water boiler for supplying water thereto; and(c) a condenser connected to said water boiler for condensing steamgenerated thereby.